The problem is the duty cycle. Not necessarily for the crank and bearings, but for all the other junk that hangs off the engine. Then you have another fundamental problem. The electrical system for these engines must be “on” all the time unlike a magneto ignition.
The injected Rotax 912 iS requires 7 switches to control it with some hope of failing safely. - Two ECU, Two fuel pumps, two alternators with failover logic dual injectors for each cylinder and dual ignition That might give some of you pause for thought. If conversion was that simple, wouldn’t everyone be doing it?